This application claims the benefit of Korean Patent Application No. 2002-1428, filed Jan. 10, 2002, in the Korean Industrial Property office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a developing system of a liquid electrophotographic image forming device, and more particularly, to a developing system of a high-concentration liquid electrophotographic image forming device having a developer supplying unit, a developer exhausting unit, and a developer collecting unit.
2. Description of the Related Art
In general, a developing system of a liquid electrophotographic image forming device forms an electrostatic latent image corresponding to a desired image by scanning light on a photosensitive medium, develops the electrostatic latent image using a developer in which powder-shaped toner is mixed with a liquid solvent, and prints the developed image on paper.
FIG. 1 is an example of a conventional developing system of a liquid electrophotographic image forming device disclosed in U.S. Pat. No. 5,255,058.
Referring to FIG. 1, the conventional developing system of the liquid electrophotographic image forming device includes a photoconductive drum 10 charged with a predetermined voltage by a photoconductor charging apparatus 14, an imaging apparatus 16 (laser scanning unit) forming an electrostatic latent image of a desired image by scanning light on the charged photoconductive drum 10 and creating a relative voltage difference representing the electrostatic image, a developer supplying unit developing the electrostatic latent image by supplying a developer to the photoconductive drum 10, and an intermediate transfer member 30 transferring the developed image of the photoconductive drum 10 and printing the transferred image onto paper 72.
The developer supplying unit prepares the developer having a concentration of less than 3% solid particles and supplies the developer between the photoconductive drum 10 and a development roller 38. For this purpose, the developer supplying unit includes concentration cartridges 82 and 84 containing a concentrated developer with a toner concentration of 25% solid, respectively, a solvent cartridge 86 containing a pure solvent, toner reservoirs 55, 57, 59, and 61 mixing the concentrated developer received from the concentration cartridges 82 and 84 with the solvent received from the solvent cartridge 86 and preparing the developer with a uniform concentration of about 2-3% solid particles, a multicolor liquid developer spray assembly 20 pumping the developer prepared in the toner reservoirs 55, 57, 59, and 61 to pumps 90, 92, 94, and 96, respectively, and supplying the developer to the development roller 38, and a collecting unit collecting an excess developer left on the photoconductive drum 10 after the electrostatic latent image is developed.
In addition, the collecting unit includes a collection container 50 collecting the developer supplied between the development roller 38 and the photoconductive drum 10 and returning the collected developer to the toner reservoirs 55, 57, 59, and 61 for each color, a squeeze roller 26 pressing the developer against the photoconductive drum 10 on which the image is developed to squeeze the solvent out of the developer contained in the developed image, and a separator 66 collecting the squeezed developer through the collection container 50, separating respective color toner from the collection container 50, and returning the solvent to a solvent reservoir 65.
In the above structure, in order to perform a development operation, the developer having four colors, such as yellow (Y), magenta (M), cyan (C), and black (K), with the concentration of about 2-3% solid particles, is provided in the toner reservoirs 55, 57, 59, and 61. In order to prepare a developer for each color, the developer supplying unit fabricates a developer with a corresponding concentration by supplying the concentrated developer from the concentration cartridges 82 and 84 and the pure solvent from the solvent cartridge 86 to the toner reservoirs 55, 57, 59, and 61, respectively. For this purpose, each of the toner reservoirs 55, 57, 59, and 61 measures the concentration of the developer containing the solvent according to a concentration sensor (not shown).
Likewise, when the developer is prepared, the development operation starts. First, the photoconductor charging apparatus 14 charges the photoconductive drum 10 with the predetermined voltage. In this state, the imaging apparatus 16 scans light on the charged photoconductive drum 10 to form the electrostatic latent image of the desired image. Subsequently, the pumps 90, 92, 94, and 96 operate such that the developer provided in the toner reservoirs 55, 57, 59, and 61 is supplied between the development roller 38 and the photoconductive drum 10 through the multicolor liquid developer spray assembly 20, thereby developing the electrostatic latent image. These charge, exposure, and development operations of four colors, such as yellow (Y), magenta (M), cyan (C), and black (K), are repeatedly and sequentially performed, and thus the developed image for each color is overlapped on the intermediate transfer member 30. The overlapped color image is printed onto the paper 72 passing through a space between the intermediate transfer member 30 and an impression roller 71.
However, since a high-concentration developer containing more than 3% solid particles cannot be directly used in the development operation, and a low-concentration developer less than 3% solid is used in the development operation, a structure of the system performing the operations from preparing the developer to supplying and collecting the developer is considerably complicated. Thus, in order to solve the problem, a new developing system of a liquid electrophotographic image forming device is required.
To solve the above and other problems, it is an object of the present invention to provide a developing system of a high-concentration liquid electrophotographic image forming device having a developer supplying unit, a developer exhausting unit, and a developer collecting unit.
Additional objects and advantageous of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, to achieve the above and other objects, there is provided a developing system of a liquid electrophotographic image forming device. The developing system includes a developer reservoir in which a developer is stored, a development container to which the developer is supplied from the developer reservoir, a development roller rotating opposite to a photosensitive drum in the development container, and a pumping portion connected between the development container and the developer reservoir via connection pipes to supply the developer to the development container from the developer reservoir, or to exhaust the developer from the development container and return the developer to the developer reservoir.
It is possible that a developer inlet/outlet is formed on a lower portion of the development container and connected to the pumping portion via the connection pipe, and the pumping portion is a tubing pump selectively supplying and exhausting the developer according to a rotational direction of a rotor installed in the pumping portion.
The system may further include a developer collecting unit collecting the developer exceeding a predetermined level in the development container and returning the developer to the developer reservoir.